OpenChainGraph Suite · ART-215 · US Mortgage Compliance

Reg Z Appendix J APR Solver

Class C · Machine-checked proof (Dafny)

Actuarial APR computation per 12 CFR 1026 Appendix J. Bracketed bisection on the general actuarial equation, with the odd-days fraction priced at simple interest per (b)(6) and only full unit-periods compounded. A rate is reported only when a sign-change bracket was established. Input for TRID APR accuracy and QM spread tests.

Reg Z Appendix J TRID APR Disclosure Bracketed Bisection Odd Days Support
🔒 All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.
Loan Parameters
Total advance disbursed at consummation.
Regular periodic payment (P&I).
Total scheduled payments (e.g. 360 for 30yr).
12 = monthly, 52 = weekly, 365 = daily.
Days from consummation to first unit period. 0 = regular.
Days in one payment period (30 for monthly).
APR Result
Loan Summary
Execution Hash (SHA-256)

Ask your agent

Copy this paragraph into Claude, OpenClaw, or any MCP-aware agent to run this exact tool, with this sample, and verify the artifact.

Run the AINumbers MCP tool `compute_reg_z_appendix_j_apr`. Task: Reg Z Appendix J actuarial APR solver.
Call it with arguments: {"policy_parameters":{"loan_amount":6000,"payment_amount":282.43,"num_payments":24,"periods_per_year":12}}
Verify before trusting: call `verify_execution_hash` on mcp.ainumbers.co (https://mcp.ainumbers.co/mcp) with the parameter `claimed_hash` set to the returned `execution_hash`, passing the full artifact the run returned (the object containing `policy_parameters` + `output_payload` + `execution_hash`; equivalently `policy_parameters` + `output_payload` with `claimed_hash`), not the bare hash string.
Return the ledger link https://ledger.ainumbers.co/ so a human can re-verify without contacting us.
PII rule: All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.
Open the tool with the sample prefilled: https://ainumbers.co/chaingraph/art-215-reg-z-appendix-j-apr.html#p=v1.H4sIAAAAAAAA_wFUAKv_eyJsb2FuX2Ftb3VudCI6NjAwMCwicGF5bWVudF9hbW91bnQiOjI4Mi40MywibnVtX3BheW1lbnRzIjoyNCwicGVyaW9kc19wZXJfeWVhciI6MTJ9ci5keFQAAAA